In recent years, plasma process apparatuses have been employed for film deposition, etching, ashing and the like in semiconductor product fabrication processes along with further miniaturization and higher integration of semiconductor products. Especially, a microwave plasma apparatus that generates plasma using microwaves tends to be more frequently used, because high density plasma can be stably generated even in a high vacuum environment, e.g., at relatively low pressures from 0.1 through 10 Pa.
Such a plasma process apparatus is disclosed in Patent Documents 1 through 6. A general plasma process apparatus is schematically explained in reference to FIG. 1, which schematically shows the general plasma process apparatus.
In FIG. 1, a plasma process apparatus 2 is provided with a susceptor 6 on which a semiconductor wafer is placed in a process chamber 4 that can be evacuated to a vacuum. At a ceiling portion opposing the susceptor 6, a disk-shaped ceiling plate 8 is hermetically provided that is made of aluminum nitride, quartz, and the like and allows microwaves to pass through.
On the upper surface of the ceiling plate 8, there are a disc-shaped planar antenna member 10 having a thickness of several millimeters, and a slow wave member 12 made of, for example, a dielectric material in order to shorten the wavelength of the microwaves, in a radial direction of the planar antenna member 10. Above the slow wave member 12, there is a ceiling cooling jacket 14 inside of which a cooling water conduit is formed in order to allow cooling water to flow through, so that the slow wave member 12 and the like are cooled. The planar antenna member 10 has plural slots 16, which are through-holes having, for example, an oblong opening shape. Generally, the slots 16 are arranged concentrically or spirally.
An inner conductive body 20 of a co-axial waveguide pipe 18 is connected to a central part of the planar antenna member 10, so that microwaves of a frequency of, for example, 2.45 GHZ generated by a microwave generator (not shown) are guided to the central part of the planar antenna member 10. The microwaves propagate in a radial direction in the planar antenna member 10, and are downwardly radiated from the slots 16 of the planar antenna member 10 into the process chamber 4 through the ceiling plate 8. Then, the microwaves generate plasma in a process space S in the process chamber 4, so that the semiconductor wafer can undergo a predetermined plasma process such as film deposition and etching.
Patent Document 1: Japanese Patent Application Laid-Open Publication No. H3-119073,
Patent Document 2: Japanese Patent Application Laid-Open Publication No. H5-343334.
Patent Document 3: Japanese Patent Application Laid-Open Publication No. H9-181052.
Patent Document 4: Japanese Patent Application Laid-Open Publication No. 2003-59919.
Patent Document 5: Japanese Patent Application Laid-Open Publication No. 2004-14262.
Patent Document 6: Japanese Patent Application Laid-Open Publication No. 2005-100931.